KR100362345B1 - Denitrification method of nitrate and nitrite using metal composition contained iron scrap and alumina scrap in water by metal scrap and device of same - Google Patents

Abstract

The present invention relates to a method and apparatus for removing aqueous nitrate nitrogen and nitrite nitrogen using a metal composition comprising iron scrap and aluminum scrap, and the present invention relates to a metal composition comprising iron scrap and aluminum scrap in a reactor. To pickle the iron scrap and aluminum scrap with hydrochloric acid, (b) removing the hydrochloric acid of the reactor and washing with water to wash the pH to the same as before the pickling, (c) washing the metal composition The denitrification step of contaminated water to fill the reactor into the reactor and then introduce the contaminated water through the inlet of the lower end of the reactor and the treated water to go through the outflow pipe of the upper end and (d) the treated water flowing out of the reactor is acid Providing a denitrification method and apparatus comprising the step of titrating to pH 6 to 8 in the outflow pipe by . The denitrification method and apparatus of the present invention was able to reduce the unit cost of the processing apparatus by using iron (Eh = -0.447V) scrap and aluminum (Eh = -1.63V) scrap, which are by-products from the polishing or cutting process of ironworks. Provided a means of recycling.

Description

FIELD OF THE INVENTION AND METHOD AND APPARATUS FOR AREA OF AQUATIUM AND NITOXIC NITROGEN USING METAL COMPOSITION CONTAINING IRON SCRAP AND ALUMINUM SCRAP.

The present invention relates to a method and apparatus for removing water-based nitric acid and nitrite nitrogen using a metal composition comprising iron scrap and aluminum scrap, and more particularly, a redox potential in a metal having a reducing property is relatively high and easily available. In particular, the present invention relates to a method and apparatus for denitrifying nitrate and nitrite nitrogen contained in sewage and wastewater with nitrogen in the air by using iron and aluminum scrap which are dead as industrial waste resources.

Recently, research on nitrogen removal has been actively conducted due to the severe eutrophication of rivers and lakes and the malignant wastewater of leachate. Nitrogen pollutants in terms of environmental pollution include manure and livestock manure, urban sewage, industrial wastewater, agricultural wastewater from fertilizers, nitrogen from sediment in lakes and rivers, and nitrogen from waste leachate. . These nitrogens are present in the form of inorganic substances such as ammonia and organic substances such as urea and proteins.

In the aquatic environment ecosystems, nitrogen pollution forms include eutrophication of lakes, river sedimentation, and red tides in the seas. In particular, groundwater contamination by leachate and various wastewaters results in increased concentrations of drinking water nitrate nitrogen. Nitrate nitrogen, produced by oxidation of ammonia nitrogen, is harmful to the human body itself. When ingested with water contaminated with nitrate nitrogen, nitrate nitrogen is absorbed into the body and reacts with hemoglobin present in the blood. The nitrate nitrogen reacted with hemoglobin is reduced to nitrite nitrogen and oxidizes the hemoglobin to metahemoglobin, thereby reducing the oxygen binding ability of the hemoglobin. This causes the disease, especially if the infant continues to drink water containing more than 10 ppm (mg / L) of nitrate nitrogen, cyanosis, or methemo globinemia: blue baby syndrome). Nitrate nitrogen is also a very widespread risk by reacting with gastric acid to form nitrosamines.

As such, nitrate nitrogen, which is harmful to humans and the environment, and nitrite nitrogen appearing in intermediate processes are used in various industrial wastewater such as livestock wastewater, fertilizer plant or starch plant, sewage treatment plant where domestic sewage flows, and large amount of fertilizer in rural areas. Denitrification methods are being developed because they contain a large amount of groundwater and cause the above problems.

Typical methods for denitrifying nitrate nitrogen and nitrite nitrogen with nitrogen in the air include biological treatment using microorganisms, selective ion exchange, air stripping and breakthrough. There are break-point chlorination, reverse osmosis, physical methods using electrodialysis, and chemical methods using fer (Hr) ₃ .

Among these biological methods, the nitrification process involves oxidizing ammonia nitrogen to nitrite nitrogen by Nitroso monas and unstable nitrite nitrogen back to nitrate nitrogen by Nitrobacter . after the nitrate nitrogen is treated through the denitrification processes to convert into nitrogen gas by means of aerobic or anaerobic denitrifying microorganisms such as Pseudomonas (Pseudomonas), micro Rhodococcus (Micrococcus), Achromobacter (Achromobacter), Bacillus (Bacillus) . The biological method is the most widely used technology in sewage treatment plants and industrial wastewater treatment facilities. However, in the denitrification process, due to the close relationship between denitrification efficiency by microorganisms and supply of carbon sources, there is a shortage of internal carbon sources. Since an external carbon source is required, cell synthesis of microorganisms involved in denitrification requires 2.47 mg of methanol for 1 mg of nitrate nitrogen. In addition, the biological method has an economical and technical problem that it is necessary to continuously supply 1.9 mg of methanol when converted according to the following formula 1 without considering cell synthesis.

[Calculation 1]

Cm = 2.47 NO ₃ ^-1 -N + 1.53 NO ₂ ^-1 -N + 0.87DO

Where Cm is the required methanol value (mg / L), NO ₃ ^-1 -N is the concentration of nitrate nitrogen to be removed (mg / L), and NO ₂ ^-1 -N is the concentration of nitrite nitrogen to be removed ( mg / L), DO represents the oxygen value consumed (mg / L).

Physical methods such as selective ion exchange, ammonia degassing, breakthrough chlorine injection, reverse osmosis, and electrodialysis are performed with nitrate and nitrite nitrogen in water rather than denitrification of nitrate and nitrite nitrogen in sewage and wastewater. It is only a protective measure to prevent the contamination of nitrogen, but it is not a real denitrification method of nitrate and nitrite nitrogen to nitrogen.

Meanwhile, a known method for removing nitrate nitrogen is Korean Patent Application No. 98-17342, which provides a method for removing nitrate nitrogen using nano-sized reducing iron powder. However, there is a problem in terms of supply and demand of large-scale sewage treatment plants or industrial wastewater treatment plants because there is a high economic cost and a small amount of production in the production of iron powder.

Accordingly, an object of the present invention is to provide a method for denitrifying aqueous nitrate nitrogen and nitrite nitrogen.

It is another object of the present invention to provide an economical and highly efficient denitrification method in water treatment.

1 shows the efficiency of removing the nitrate nitrogen and nitrite nitrogen by the denitrification apparatus of the present invention when the aluminum scrap ratio to iron scrap is 20: 1,

Figure 2 shows a schematic diagram of the denitrification apparatus of the present invention.

In order to achieve the above object, the present invention provides a metal composition comprising iron scrap and aluminum scrap for removal of aqueous nitrate nitrogen and nitrite nitrogen.

In addition, the present invention (a) putting the metal composition in the reaction tank and washing the metal composition with hydrochloric acid, (b) removing the hydrochloric acid of the reaction tank and washed with water to wash the pH in the same manner as before the pickling, (c) denitrification of contaminated water by filling the washed metal composition in the reaction vessel, and then introducing the contaminated water through the inlet of the lower end of the reaction vessel and leaving the treated water through the outlet water pipe of the upper end; and (d) in the reaction tank. The outflowing treated water provides a method for denitrifying nitrate nitrogen and nitrite nitrogen comprising treating the acid to titrate the pH to 6 to 8 in the outflow pipe.

In addition, the present invention is connected to the inlet pipe (2) at the bottom of the reaction tank (3) filled with a metal composition, there is a pump (1) for controlling the speed of the contaminated water at the inlet pipe inlet, The denitrification apparatus of FIG. 2 is characterized in that a sludge receiver 4 to which denitrified treated water moves is connected, and an outlet pipe 6 equipped with a pH meter 5 is connected to the sludge receiver.

Hereinafter, the present invention will be described in detail.

The inventors of the present invention have already suggested that the unit cost of nano-sized iron powder is 250 to 300 times more expensive than micro-sized iron powder, and denitrification of nitrate nitrogen (NO ₃ ^-- N) and nitrite nitrogen (NO ₂ ^-- N). The present invention has been completed by focusing on the lack of practical practicality. The present invention used metal scrap discharged as waste for denitrification. Metal scrap has a problem in terms of supply and demand in the process of large scale sewage treatment plant or industrial wastewater treatment plant because the invention using reduced iron powder has high production cost and small quantity. The manufacturing cost is 800 to 1000 times compared to the powder, and industrial waste can be usefully applied to the actual contaminated water treatment process. In addition, it is possible to increase the denitrification efficiency by using various kinds of metal scraps.

The present invention provides a metal composition comprising a metal scrap capable of denitrifying aqueous nitrate nitrogen or nitrite nitrogen. The water system is preferably sewage, waste water, groundwater and sewage, and the metal composition is preferably a metal scrap collected from ironworks and the like, and more preferably iron scrap and aluminum scrap, which are by-products from cutting or polishing. The metal composition of the present invention is preferably in the ratio of iron scrap to aluminum scrap mass ratio of 20: 1 to 10: 1, or in a volume ratio of 4: 1 to 1: 1. The ratio of the aluminum scrap to the iron scrap is preferably adjusted to a higher ratio of iron or aluminum as the concentration of nitrate and nitrite nitrogen in the reaction tank is higher. In addition, the metal composition further comprises 10 to 20% by weight of the metal composition, such as scrap of zinc used as a paint or a polymer, zinc powder, tin used as an alloying material.

Method of removing the nitrate nitrogen or nitrite nitrogen of the present invention comprises the steps of (a) putting a metal composition comprising iron scrap and aluminum scrap in the reaction tank filled with 1-4% hydrochloric acid and then pickling the metal composition, ( b) a washing step of removing hydrochloric acid from the reactor and washing with water to titrate the pH in the same manner as before the pickling, (c) filling the finished metal composition into the reactor, and then introducing contaminated water through the inlet of the bottom of the reactor. Denitrification of the contaminated water to the treated water to go through the effluent pipe at the upper end, and (d) the treated water flowing out of the reaction tank to the acid treatment to titrate the pH 6 to 8 in the effluent pipe It is characterized by. In the metal composition comprising the iron scrap and the aluminum scrap of the present invention, the iron scrap to aluminum scrap mass ratio is 20: 1 to 10: 1, or the volume ratio is preferably 4: 1 to 1: 1. The ratio of the aluminum scrap to the iron scrap is preferably adjusted to a higher ratio of iron or aluminum as the concentration of nitrate and nitrite nitrogen in the reaction tank is higher.

In addition, the denitrification method of the present invention further includes an oil film removing step of pretreatment of the metal composition. Since the metal composition of the present invention uses an organic solvent called cutting oil to reduce friction with milling and reduce damage and abrasion of the machine during cutting or polishing, cutting oil is applied to the surface of the metal composition to form an oil film. Since the oil film of the metal composition has an inhibitory effect on the surface reaction of the metal, the oil film is subjected to a process of removing the oil film. The film removal process of the metal composition is commonly referred to as degreasing and the film removal of the metal composition of the present invention is preferably selected from the group consisting of a volatile solvent, an alkali solvent and heat, and more preferably cutting oil using heat. It is preferable to remove the oil film coated on the surface of the metal composition by heating to a flash point of 190 ℃ or more. Iron scrap of the present invention is most preferably maintained for 5 minutes at 250 to 350 ℃ and aluminum scrap for about 5 minutes at 250 ℃ degreasing.

Step (a) and (b) of the present invention is to remove the impurities attached to the metal composition by washing the metal composition collected in the ironworks and the like to increase the efficiency of the denitrification reaction of the metal composition, and by washing with water ( The pH lowered by the pickling in step a) is restored to pH 5 or higher in normal operation, and the hydrochloric acid remaining on the surface of the metal composition is removed to prevent corrosion easily. In the pickling process, after filling with hydrochloric acid, it is preferably left for 30 minutes to 1 hour or by pouring the pickling hydrochloric acid solution for 1 hour at the inlet of the contaminated water. The impurities removed from the surface of the metal composition by the pickling are dissolved in water or removed by water pressure (very low, ie flowing water level).

In addition, the steps (a) and (b) are more targeted to the metal composition filled in the reaction tank to prevent the reaction efficiency is lowered by the by-products generated during the denitrification process when carried out by the denitrification method of the present invention. Conduct. The cycle of pickling is different depending on the concentrations of nitrate and nitrite nitrogen in the reaction tank, but after denitrifying the contaminated water, the treatment efficiency of the contaminated water is less than 20% or exceeded the reference value, or is usually two weeks. Pickling at a cycle of 3 weeks is preferable, and the method is the same as the steps (a) and (b).

The denitrification method of the present invention not only purifies contaminated water by denitrifying nitrite nitrogen or nitrate nitrogen contained in contaminated water, but also continuously supplying organic carbon sources of biological methods using existing microorganisms and methods using only nano-size metal iron. It is a way to solve industrial economic problems and to recycle industrial waste resources.

The present invention also provides a denitrification apparatus. As shown in FIG. 2, the denitrification apparatus of the present invention includes a pump 1, an inlet pipe 2, a reaction tank 3, a sludge receiver 4, a pH meter 5, and an outlet pipe 6. It is characterized by. The denitrification apparatus can be further applied, developed and used as the most basic mechanism. The denitrification apparatus is filled with a metal composition including iron scrap and aluminum scrap in a reaction tank, and contaminated water is introduced through an inlet pipe using a pump. At this time, the pump controls the residence time of the contaminated water in the reaction tank by adjusting the inflow rate according to the concentration of the contaminated water. The rate of inflow of contaminated water depends on the degree of contamination. The treated water flowing out of the reaction tank is moved to the sludge receiver of the circular plate through the sawtooth of the upper part of the reaction tank, and then is discharged to the outlet pipe through the pH meter. The sludge receiver accumulates sludge contained in the treated water flowing out of the reaction tank to prevent the sludge from flowing out through the outflow pipe. In addition, the pH meter is installed in the outlet tube to titrate the pH of the treated water to 7 to 8.5.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are provided only to more easily understand the present invention, and the present invention is not limited to the following examples.

Example 1

Samples and Metal Compositions Used in the Invention:

Iron and aluminum scrap was used as scrap from the grinding and cutting process in ironworks. The iron scrap at this time is a metal iron known as carbon steel, containing 0.45 to 0.60% of carbon, containing less than 0.5% of silicon and manganese, and having a rounded stainless steel scrubber shape. Aluminum scrap was used as scrap from the cutting of aluminum nodules containing no other impurities. This is also a stainless steel scrubber. They had a large amount of coolant in the cutting process, and the coolant was removed after drying and used. The pretreatment was performed by heat using a conventional degreasing method. Iron scrap was maintained at 250 to 350 ° C. for about 5 minutes and aluminum was maintained at 250 ° C. for about 5 minutes to remove the cutting oil film coated on the scrap surface.

Denitrification: Iron and aluminum scrap are pickled with hydrochloric acid solution diluted to 2.5% for 1 hour, followed by washing with water to adjust the pH to above pH 5 before pickling. The acid-treated metal scrap was filled into the reaction tank with aluminum scrap at a ratio of 20: 1 by weight, and the contaminated water was flowed at a flow rate at which the residence time in the reactor was maintained for 2 to 10 hours using a pump. While contacting the metal scrap filled in the reaction vessel at room temperature. The denitrified contaminated water was discharged by adjusting the pH to 7 through the outlet pipe at the upper end of the reactor. Denitrification efficiency was analyzed by ion chromatography (Waters, USA) for nitric or nitrite nitrogen.

Example 2

It carried out similarly to Example 1 except having adjusted the mass ratio of iron and aluminum scrap which is a metal composition to 10: 1.

Example 3

After denitrifying contaminated water, if the treatment efficiency is less than 20% or outflowed above the standard, the metal composition in the reactor is treated with the same surface as the pickling process or pickled at the inlet of contaminated water. The hydrochloric acid solution was flowed and washed with water after the 1 hour residence time, and the same procedure as in Example 1 was carried out.

Example 4

The iron composition of Example 1 was mixed with zinc powder 10% by weight in a metal composition of 20: 1 was mixed in the same manner as in Example 1.

Example 5

In the metal composition in which the iron and aluminum of Example 1 was mixed at 20: 1, zinc lumps were mixed at 10 wt%, and the same method as in Example 1 was performed.

Example 6

Tin powder was mixed in a metal composition in which iron and aluminum of Example 1 were mixed at 20: 1 by 10% by weight, and the same procedure as in Example 1 was performed.

Experimental Example

Example 1, Example 2, Example 4, Example 5, Example 6 was applied to the site to confirm the denitrification efficiency. The contaminated water was actually adjusted to 150 ppm of nitrate nitrogen and 250 ppm of nitrite nitrogen for the experiment at high concentration in the initial influent of the sewage treatment plant. The following experiment was carried out in the same manner as in Example 1. Table 1 below shows the efficiency of the denitrification reaction of Example 1 and Example 2 of the present invention.

TABLE 1

Residence time Example 1 Example 2 Nitrate Nitrogen (NO ₃ ^-1 -N) Nitrous acid nitrogen (NO ₂ ^-1 -N) Nitrate Nitrogen (NO ₃ ^-1 -N) Nitrous acid nitrogen (NO ₂ ^-1 -N) 0 150 ppm 250 ppm 150 ppm 250 ppm 2 119 ppm 163 ppm 97 ppm 131 ppm 4 92 ppm 89 ppm 63 ppm 75 ppm 6 63 ppm 52 ppm 25 ppm 29 ppm 8 28 ppm 19 ppm 6 ppm 4 ppm 10 4 ppm 2 ppm 0 ppm 0 ppm

As shown in Table 1 above, as a result of producing a contaminated water of high concentrations of nitrate and nitrite nitrogen of about 8-10 times based on the average domestic total nitrogen of the influent of sewage treatment plant, the treatment efficiency of more than 80% after 8 hours of residence time Showed. In addition, the treatment efficiency is improved by increasing the amount of aluminum scrap, but if the amount is increased to 10: 1 or more, the oxide produced during the denitrification of aluminum scrap in the long-term operation may cause a rapid inhibition of the reaction efficiency.

1 is a diagram showing the efficiency of removing the nitrate nitrogen and nitrite nitrogen when the denitrification apparatus of the present invention when the aluminum scrap ratio of the iron scrap contained in the metal composition of the present invention is 20: 1, The removal rate (mg / L) after 1 day in the reaction tank of nitrate nitrogen, ○ indicates the removal rate (mg / L) after 1 day in the reaction tank of nitrite nitrogen, and the ▼ after 14 days in the reaction tank of nitrate nitrogen. The removal rate (mg / L), ▽ is the removal rate (mg / L) after 14 days in the nitrous nitrogen reaction tank, ■ is the removal rate (mg / L) in the reaction tank pickled after 14 days of nitrate nitrogen, □ indicates the removal rate (mg / L) in the pickling tank after 14 days of nitrite nitrogen. According to FIG. 1, when iron and aluminum scraps were treated with a mass ratio of 20: 1, after 14 days, the treatment efficiency in the reactor was reduced by about 15-20% for the same contaminated water. However, when the treatment efficiency decreases as the reaction proceeds, the reaction efficiency similar to that of the initial stage can be maintained by pickling using a hydrochloric acid solution as in Example 3.

Table 2 below shows the degree of denitrification of Example 4, Example 5 and Example 6.

TABLE 2

Residence time Example 4 Example 5 Example 6 Nitrate Nitrogen (NO ₃ ^-1 -N) Nitrous acid nitrogen (NO ₂ ^-1 -N) Nitrate Nitrogen (NO ₃ ^-1 -N) Nitrous acid nitrogen (NO ₂ ^-1 -N) Nitrate Nitrogen (NO ₃ ^-1 -N) Nitrous acid nitrogen (NO ₂ ^-1 -N) 0 150 ppm 250 ppm 150 ppm 250 ppm 150 ppm 250 ppm 2 103 ppm 142 ppm 120 ppm 151 ppm 125 ppm 174 ppm 4 57 ppm 76 ppm 82 ppm 95 ppm 101 ppm 106 ppm 6 14 ppm 21 ppm 44 ppm 71 ppm 57 ppm 77 ppm 8 3 ppm 0 ppm 23 ppm 22 ppm 13 ppm 29 ppm 10 0 ppm 0 ppm 0 ppm 5 ppm 0 ppm 11 ppm

As shown in Table 2, Example 4 was superior to the denitrification degree compared to the metal composition containing iron and aluminum by further mixing the zinc powder in the metal composition. In addition, Example 5 and Example 6 showed almost the same effect as Example 1.

In addition, the polluted water flowing into Guri-si Sewage Treatment Plant was used directly on site. The following experiment was carried out in the same manner as in Example 1. As a result, domestic sewage with 17.7 ppm of nitrate nitrogen and 7.8 ppm of nitrite nitrogen was completely treated in the reactor within 1 hour of residence time.

[Comparative Example]

Except for using only the iron scrap in place of the mixed scrap of iron and aluminum, the experiments were the same as in Examples 1 and 2, the results are shown in Table 3.

TABLE 3

Residence time Iron scrap Nitrate Nitrogen (NO ₃ ^-1 -N) Nitrous acid nitrogen (NO ₂ ^-1 -N) 0 150 250 2 142 204 4 129 179 6 106 152 8 95 138 10 74 103

As shown in Table 3, 51% of nitrate nitrogen and 69% of nitrate nitrogen were denitrated after 10 hours of diesel residence time using only iron scrap. These results were significantly lower than the denitrification efficiency of the metal composition of the present invention of the experimental example.

As mentioned above, the denitrification method using a metal composition comprising iron scrap and aluminum scrap of the present invention is a leather factory, livestock wastewater, fertilizer factory and sewage treatment plant, etc., contaminated with an excess of nitrate nitrogen and nitrite nitrogen. Effectively denitrates contaminated water. In addition, the denitrification method using the metal composition of the present invention can solve the economic problems caused by the continuous supply of the organic carbon source of the conventional biological method using microorganisms and the method using only nano-size metal iron and recycle industrial waste resources.

Claims (9)

(delete) (delete) (a) placing a metal composition comprising iron scrap and aluminum scrap in a reactor and pickling the metal composition with hydrochloric acid; (b) a washing step of removing hydrochloric acid from the reactor and washing with water to titrate the pH in the same manner as before pickling; (c) denitrification of the contaminated water by filling the washed metal composition in the reaction tank and then introducing the contaminated water through the inlet of the lower end of the reaction tank and allowing the treated water to exit through the outlet water pipe of the upper end; And (d) the treated water flowing out of the reaction tank is treated with an acid to titrate the pH to 6 to 8 in the outflow pipe A method for denitrifying nitrate nitrogen and nitrite nitrogen comprising a. The nitrate nitrogen according to claim 3, wherein the metal composition further comprises 10 to 20% by weight of at least one selected from the group consisting of scrap of zinc, zinc powder and tin used as a paint or a polymerizer. And a method for denitrifying nitrous nitrogen. The method of claim 3, wherein the denitrification method further comprises the step of removing the oil film coated on the surface of the metal composition by heating the metal composition to at least 190 ℃, the flash point of the cutting oil, before step (a). A method for denitrifying nitrate nitrogen and nitrite nitrogen. 4. The method for denitrifying nitrate nitrogen and nitrite nitrogen according to claim 3, wherein the metal composition filled in the reaction tank in step (c) comprises iron scrap to aluminum scrap in a ratio of 20: 1 to 10: 1. . 4. The method for denitrifying nitrate nitrogen and nitrite nitrogen according to claim 3, wherein the metal composition filled in the reactor in step (c) comprises iron scrap to aluminum scrap in a volume ratio of 4: 1 to 1: 1. . 4. The method of claim 3, wherein step (c) denitrifies nitrate nitrogen or nitrite nitrogen in contaminated water with nitrogen. An inlet pipe 2 is connected to the lower end of the reaction tank 3 filled with the metal composition, a pump 1 for controlling the speed of the contaminated water at the inlet of the inlet pipe, and the treated water denitrated at the upper end of the reaction tank. The denitrification apparatus of FIG. 2, wherein a moving sludge receiver (4) is connected, and an outlet pipe (6) equipped with a pH meter (5) is connected to the sludge receiver.